[biologie] herbiciden

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herbiciden

Hoi ik heb een paar vraagjes over herbiciden, wat me nog onduidelijk is

wordt er na toediening van een herbicide minder NADP gereduceerd tot NADPH?

en verminderen herbiciden de bruto productie van glucose in onkruid?

remmen herbiciden de dissimilatie in onkruid?

alvast bedankt

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Re: herbiciden

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"In biotech moet je soms dingen doen waarvan anderen zeggen dat het onmogelijk is."

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Re: herbiciden

het enige wat ik er zó van weet is dat verschillende (groepen van) herbiciden op verschillende manieren ingrijpen in het metabolisme van de plant.

een voorbeeld is glyfosaat (roundup)

http://www.greenpast.../?objectID=7213

UNDERSTANDING GLYPHOSATE

Glyphosate (N-(phosphomonomethyl)glycine) is a strong metal chelator and was first patented as such by Stauffer Chemical Co. in 1964 (U.S. Patent No. 3,160,632). Metal chelates are used extensively in agriculture to increase solubility or uptake of essential micronutrients that are essential for plant physiological processes. They are also used as herbicides and other biocides (nitrification inhibitors, fungicides, plant growth regulators, etc.) where they immobilize specific metal co-factors (Cu, Fe, Mn, Ni, Zn) essential for enzyme activity. In contrast to some compounds that chelate with a single or few metal species, glyphosate is a broadspectrum chelator with both macro and micronutrients (Ca, Mg, Cu, Fe, Mn, Ni, Zn). It is this strong, broadspectrum chelating ability that also makes glyphosate a broad-spectrum herbicide and a potent antimicrobial agent since the function of numerous essential enzymes is affected (Ganson and Jensen, 1988).

Primary emphasis in understanding glyphosate’s herbicidal activity has been on inhibition of the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) at the start of the Shikimate physiological pathway for secondary metabolism. This enzyme requires reduced FMN as a co-factor (catalyst) whose reduction requires manganese (Mn). Thus, by immobilizing Mn by chelation, glyphosate denies the availability of reduced FMN for the EPSPS enzyme. It also can affect up to 25 other plant enzymes that require Mn as a co-factor and numerous other enzymes in both primary and secondary metabolism that require other metal co-factors (Co, Cu, Fe, Mg, Ni, Zn). Several of these enzymes also function with Mn in the Shikimate pathway that is responsible for plant responses to stress and defense against pathogens (amino acids, hormones, lignin, phytoalexins, flavenoids, phenols, etc.). By inhibiting enzymes in the Shikimate pathway, a plant becomes highly susceptible to various ubiquitous soilborne pathogens (Fusarium, Pythium, Phytophthora, Rhizoctonia, etc.). It is this pathogenic activity that actually kills the plant as “the herbicidal mode of action” (Johal and Rahe, 1984; Levesque and Rahe, 1992, Johal and Huber, 2009). If glyphosate is not translocated to the roots because of stem boring insects or other disruption of the vascular system, aerial parts of the plant may be stunted, but the plant is not killed.
een vlot literatuuronderzoekje moet je in een paar uur aardig wat kunnen leren van verschillende (groepen) herbiciden en hun werking. Literatuur zat, al is het alleen maar vanwege de al of niet vermeende milieu-effecten van het gebruik ervan.
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